For : - Get out (of my sight)/get lost = casses-toi, dégage d'ici, barres-toi (familiar) - Let them leave = laisse-les partir (correct) Nota bene : "s'en va" does not exist without a subject like "il" or "elle" (he/she). And we would rather tell : "Va t-en, laisse-moi tranquille/laisse-moi en paix" "Va-y, c'est bon, va t-en maintenant, je suis las de parler avec toi..." = C'mon, right now, go away, I'm weary to speak with you...

The verb is "s'en aller". It means "to go (away)". So if you want to say "let them go", you can say "laisse (let) les (them) s'en aller" If you want to say "get away !" you will say " va-t'en !", it's the imperative form of "tu t'en vas". It's not as complicated as you seem to think :)

"let them leave" = "laisses les partir" "get out of here/get away" = "pars d'ici" "s'en va" is for him/her = il/elle s'en va and "s'en va" alone doesnt mean anything... right, for them it's "ils/elles s'en vont" i = je m'en vais you = tu t'en vas we = nous nous en allons Hope I help you =)